1. Field of the Invention
The present invention relates to a navigation system, and more particularly, to a method for detecting a map matching position of a vehicle in a navigation system, which detects coordinates on a link (road) of map data that will be matched to coordinates of a current vehicle location obtained from navigation messages received by a GPS (global positioning system) receiver and from detection signals of a variety of sensors installed at a vehicle to detect a travel state of the vehicle.
More specifically, the present invention relates to a method for detecting a map matching position of a vehicle in a navigation system, wherein coordinates of a current vehicle location are obtained from navigation messages received by a GPS receiver and from signals of sensors installed at a vehicle, using a general line equation for obtaining an intersection point between an arbitrary line and a perpendicular line drawn from an arbitrary point to the line, and the current vehicle location is matched to coordinates found through orthogonal projection on a link on map data closest to the obtained coordinates of the current vehicle location.
2. Description of the Related Art
Generally, a navigation system obtains coordinates of a current vehicle location using navigation messages transmitted by a plurality of GPS satellites arranged on geostationary orbits over the Earth and using detection signals of a plurality of sensors installed at a vehicle, including a gyro sensor for detecting a travel direction of the vehicle and a speed sensor for detecting a travel speed, matches the obtained coordinates of the current vehicle location to map data, searches for a travel path from the matched coordinates of the current vehicle location to coordinates of a destination of the vehicle through the map data, and guides the travel of the vehicle to the destination along the searched travel path.
In such a navigation system, the coordinates of the current vehicle location obtained from the navigation messages received by the GPS receiver and the detection signals of the sensors should be exactly matched to a link on the map data in order to correctly detect the coordinates of the current vehicle location, inform a user of the detected coordinates, correctly search for the travel path from the coordinates of the current vehicle location to the coordinates of the destination, and guide the vehicle along the searched travel path.
A conventional technique for matching coordinates of a current vehicle location to coordinates of a link on map data is disclosed in Korean Patent Application No. 1997-78443 (Laid-Open Publication No. 1999-58343). According to the conventional technique, coordinates of a current vehicle location is detected and it is determined whether the detected coordinates of the current vehicle location fall within an interpolation range of a link on map data. If it is determined that the detected coordinates of the current vehicle location fall within the interpolation range of the link on the map data, a distance between coordinates of interpolated points positioned in the interpolation range and the coordinates of the current vehicle location is calculated. The coordinates of an interpolated point in which the calculated distance is smallest are selected as coordinates of a target interpolation point. Then, the coordinates of the current vehicle location are substituted with and matched to the coordinates of the selected target interpolation point. In such a manner, a travel path of the vehicle is tracked.
However, since the conventional technique substitutes the coordinates of the current vehicle location with the coordinates of the interpolated point on a link without searching for correct coordinates on the link of the map data to be matched to the coordinates of the current vehicle location, there is a problem in that it is not possible to correctly search for coordinates of an interpolated point to be matched to the coordinates of the current vehicle location if the coordinates of the current vehicle location exist between coordinates of two adjacent interpolated points.